Field of the Invention
The present invention generally relates to the field of diagnostic tools to assess the metabolism of nutrients. More specifically, the present invention relates to a method for diagnosing impaired absorption of amino acids, monosaccharides and fatty acids using stable isotopologues of amino acids.
Description of the Related Art
Intestinal absorption of amino acids, monosaccharides and fatty acids are essential for human metabolism. Impaired absorption of amino acids via the intestinal wall, which occurs in patients with intestinal failure, can lead to involuntary, potentially lethal weight loss and muscle wasting. Therefore, it is imperative to diagnose impaired absorption of these nutrients before it causes significant damage to a patient's health.
Current methods, however, only measure combined digestion and absorption of nutrients and thus cannot distinguish impaired absorption from impaired digestion. While impaired digestion may affect a patient's health, it can be easily treated with supplementation of digestive enzymes. Impaired absorption, on the other hand, may require more medical attention. In addition, these methods often show accuracies in determining the exact value of nutrients absorption.
For instance, a commonly used method to determine protein digestion/absorption includes feeding the patients intrinsically labeled proteins. In this method, plants or animals are fed with labeled amino acids. The patient then consumes resultant proteins from plants, meat or milk. The blood of the patient can then be sampled to measure the uptake of protein by the intestine. However, besides not being able to distinguish impaired absorption from impaired digestion, it is challenging to obtain large amount of proteins that contain sufficiently labeled amino acids for accurate detection. Furthermore, fecal loss analysis, which is considered as the gold standard for analysis of nutrient metabolism, is a poor indicator of the uptake of amino acids since unabsorbed amino acids can be partly metabolized by bacteria into ammonia and subsequently absorbed by the colon mucosa, resulting in undetectable nitrogen loss and false results for amino acid metabolism.
Thus, there is a recognized need in the art for a method of accurately and distinguishably measuring nutrient, such as, amino acids, monosaccharides and fatty acids absorption. Particularly, the prior art is deficient in these aspects. The present invention fulfills this long standing need and desire in the art.